| Scoop Product Limited | Information & communication | 2022 |
| Scoosh Live Ltd | Education | 2020 |
| Scotsbridge Capital Ltd | Professional & scientific | 2019 |
| Scribe MGA Limited | Financial services | 2025 |
| Scruffs Doggy Day Care Limited | Other services | 2024 |
| SCS Concept Group UK Ltd | Manufacturing | 2023 |
| SCS Construction (Berkshire) Limited | Construction | 2015 |
| Scully Growth Consultants Limited | Professional & scientific | 2025 |
| SD Automotive Repairs Ltd | Wholesale & retail | 2024 |
| SD Care Services (Swindon) Ltd | Health & social care | 2018 |
| SDO Associates Limited | Professional & scientific | 2022 |
| Sdortho Limited | Health & social care | 2020 |
| SDS Consultancies Ltd | Financial services | 2025 |
| SDS Living Ltd | Real estate | 2024 |
| Sdue Technology Services Ltd | Information & communication | 2015 |
| Sdys Bricklayers Limited | Construction | 2017 |
| SE Accounting Group Ltd | Professional & scientific | 2025 |
| SE Andover Bess Ltd | Professional & scientific | 2022 |
| SE Dylan Ltd | Professional & scientific | 2022 |
| SE Essington Bess Ltd | Energy | 2023 |
| SE Financial Group Ltd | Professional & scientific | 2025 |
| SE Goval Bess Ltd | Professional & scientific | 2022 |
| SE Holdings Global Ltd | Financial services | 2025 |
| SE Investment Group Ltd | Financial services | 2025 |
| SE Lockerley Bess Ltd | Professional & scientific | 2022 |
| SE Mannington Bess Ltd | Energy | 2023 |
| SE Myrddin Ltd | Professional & scientific | 2022 |
| SE Pendragon Ltd | Professional & scientific | 2022 |
| SE Portwind Ltd | Professional & scientific | 2022 |
| SE Upper Studley Bess Ltd | Professional & scientific | 2022 |
| SE Wealth Management Ltd | Financial services | 2013 |
| Seabear Property Ltd | Real estate | 2024 |
| Seabreeze Marine Consultancy Limited | Administrative & support | 2009 |
| Seacon (Europe) Limited | Manufacturing | 1987 |
| Seafood Safety Assessment Limited | Hospitality | 2014 |
| Sealey Electrical & Stadia Ltd | Construction | 2026 |
| Sears Maverick Trading Limited | Wholesale & retail | 2020 |
| Seavoyant Ltd | Extraterritorial | 2024 |
| Sebcon Ltd | Transport & logistics | 2019 |
| Secareserve Ltd | Health & social care | 2016 |
| Secmon Ltd | Information & communication | 2020 |
| Second Snuggle Limited | Wholesale & retail | 2023 |
| Secret Beauty Salon Ltd | Other services | 2023 |
| Sector 3 Consulting Ltd | Professional & scientific | 2025 |
| Secure Data Media Solutions Limited | Information & communication | 2000 |
| Secure Ironmongery Supplies Ltd | Wholesale & retail | 2017 |
| Secure Roofing SW Ltd | Construction | 2024 |
| Secure Safety Solutions Ltd | Professional & scientific | 2019 |
| Secure Waste Cleaning Services Limited | Administrative & support | 2019 |
| Secure Waste Limited | Water & waste | 2012 |
| Securicode Ltd | Manufacturing | 2004 |
| See:Saw Clothing Ltd | Wholesale & retail | 2012 |
| Seebeck 87 Limited | Financial services | 2012 |
| Seer 365 Ltd | Information & communication | 2020 |
| Segdale Ltd | Professional & scientific | 2017 |
| Segment Pulse Limited | Professional & scientific | 2007 |
| Seige Ltd | Extraterritorial | 2014 |
| Sejranaj Holding Ltd | Real estate | 2025 |
| SEL Fire Ltd | Construction | 2017 |
| Selba Plastering Ltd | Construction | 2019 |
| Select Line Carpets & Floorings Limited | Construction | 1990 |
| Select Line Kitchen & Flooring Studio Ltd | Wholesale & retail | 2015 |
| Select Support IT Limited | Information & communication | 2013 |
| Selene Muse Limited | Wholesale & retail | 2025 |
| Self Care Counselling Limited | Health & social care | 2024 |
| Self Made Creatives Limited | Education | 2025 |
| Self Storage Swindon Ltd | Other services | 2023 |
| Sellfish Direct Ltd | Wholesale & retail | 2020 |
| Selling a Franchise Limited | Professional & scientific | 2016 |
| Selwoods Upholstery Ltd | Manufacturing | 2019 |
| SEM Property Investment Limited | Real estate | 2025 |
| Semantix Solutions Ltd | Information & communication | 2014 |
| Semtek Music Ltd | Information & communication | 2019 |
| Senkin Ltd | Professional & scientific | 2019 |
| Sensata Technologies (Europe) Limited | Professional & scientific | 2003 |
| Sensata Technologies Holding Company U.K. | Administrative & support | 2006 |
| Sensata Technologies Intermediate UK Limited | Financial services | 2018 |
| Sensata Technologies UK Financing Co. Limited | Financial services | 2015 |
| Sense EIA Limited | Professional & scientific | 2015 |
| Senseeia Consulting Limited | Professional & scientific | 2018 |
| Senseekers Ltd | Wholesale & retail | 2024 |
| Sentinel Roofcare Ltd | Construction | 2024 |
| Seqrity Codes Ltd | Wholesale & retail | 2025 |
| Sequoia Healthcare Ltd | Wholesale & retail | 2022 |
| Seraph Partnership LLP | | 2022 |
| Seren Delta Consulting Limited | Information & communication | 2025 |
| Serena Consultants Ltd | Administrative & support | 2026 |
| Serendib Property Ltd | Real estate | 2025 |
| Serendipity Gifts and Treats Ltd | Wholesale & retail | 2022 |
| Serene 247 Solutions Ltd | Health & social care | 2025 |
| Serene Healthcare Services Ltd | Administrative & support | 2016 |
| Serene Healthcare Supply Ltd | Administrative & support | 2025 |
| Serene Portfolio Ltd | Real estate | 2025 |
| Sergiu Moldovan Ltd | Transport & logistics | 2023 |
| Sernyaamo Care Services Ltd | Health & social care | 2023 |
| Servants Fellowship International | Education | 1979 |
| Serve U Coaching Limited | Arts & recreation | 1996 |
| Service Tmjblinds.Uk Ltd | Construction | 2023 |
| Sesmedevent Ltd | Health & social care | 2019 |
| SET Square Designs Ltd | Construction | 2013 |